Jonah's Aquarium in Thousand Oaks, Cal. lists them. They were out when I tried to order them several months ago.
I ordered mine from Sachs Systems in Fla. Try "www.aquaculturestore.com" . Paul Sachs was the person I spoke to. They were shipped in ice chest via overnite mail. 17 of the 20 made the flight and survived.
I stocked them in an intermittent creek that flows thru my property and has 2 mud holes that retain water, but get too low (I think) for bass.
Warmouth are bream with an attitude.